Eco diesel Suspension bottoming out on normal roads

[Barbarian]

Last thing, I’m going to do a 4 wheel weight measurement sometime next week. Wouldn’t surprise me if the springs moved about 500 pounds front to rear. Which would help with the extra diesel weight

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[Dougstdig]

Last thing, I’m going to do a 4 wheel weight measurement sometime next week. Wouldn’t surprise me if the springs moved about 500 pounds front to rear. Which would help with the extra diesel weight

I don’t think you’ll find near that much difference, if any at all with limited amount of movement. I’d be interested to see if I’m wrong though.

 

[ajkaz]

Thanks for this info!

I’m absolutely not opposed to adding hydraulic or pneumatic bump stops. One thing I’ve not been able to answer yet is what is the reason the bump stop tube or shaft is longer on the diesel models? I’ll go on a limb and guess that the diesel motors have pieces parts that hang down further than the 3.6 L motor does. I don’t know exactly what the low point is but I question if it is the upper control arm mount either on the top of the differential or the one on the passenger side. Whoever installed your set up, were they able to tell you what it was and how did they determine how much of the bump stop tube to remove in order to install the hydraulic set up ?

I was looking at this yesterday. The differential and UCA mount fit tightly in a cavity right below the motor. It looks like a heat exchanger hanging off the motor is right above where the pumpkin stops. Lots going on under there... Noticed some ATF ever so slightly seeping from where the trans and TC meet.... not good.

 

[Dougstdig]

I was looking at this yesterday. The differential and UCA mount fit tightly in a cavity right below the motor. It looks like a heat exchanger hanging off the motor is right above where the pumpkin stops. Lots going on under there... Noticed some ATF ever so slightly seeping from where the trans and TC meet.... not good.

That’s what I figured. Over the weekend I read in several posts that a fella was looking for increased upward flex…which I’d strongly recommend against. If looking for additional travel stick with increasing droop. Be very observant when dialing in bump stop increases as lift is increased. Thanks again for peaking.

 

[domingjm]

That’s what I figured. Over the weekend I read in several posts that a fella was looking for increased upward flex…which I’d strongly recommend against. If looking for additional travel stick with increasing droop. Be very observant when dialing in bump stop increases as lift is increased. Thanks again for peaking.

Apologies for my naivety, I'm in the process of learning all of this terminology. Does this have implications for a run of the mill 2.5" suspension lift kit?

 

[Dougstdig]

Apologies for my naivety, I'm in the process of learning all of this terminology. Does this have implications for a run of the mill 2.5" suspension lift kit?

If I understand your question correctly…no it shouldn’t. It appears to be more critical on Diesel models, but even gassers will have bump stop spacers equal to that of the lift of the spring.

The rear is less critical, but on diesel front ends, the tube which houses the bump stop in the center of the spring is longer limiting upward travel. This is not a horrible thing. There are things we can do with a fender flares if need be to either increase the size of the tire and or increase full stuff articulation without contact.

 

[domingjm]

If I understand your question correctly…no it shouldn’t. It appears to be more critical on Diesel models, but even gassers will have bump stop spacers equal to that of the lift of the spring.

The rear is less critical, but on diesel front ends, the tube which houses the bump stop in the center of the spring is longer limiting upward travel. This is not a horrible thing. There are things we can do with a fender flares if need be to either increase the size of the tire and or increase full stuff articulation without contact.

So increasing the compressed length of the coil (e.g., by ~2.5") should push the bump stop further away and mitigate this problem, right? And/or increasing the stiffness of the coil?

 

[Dougstdig]

So increasing the compressed length of the coil (e.g., by ~2.5") should push the bump stop further away and mitigate this problem, right? And/or increasing the stiffness of the coil?

What ever the ‘special sauce’ is…differs from manufacturer to manufacturer. Ultimately, the axle has high points, upper control arm mounts for example, and they can only go up so far before making contact with the motor components…and tires with fenders. On the Mopar kit for example, their 2” lift has 2” bump stop extensions that mount to the spring pad on the axle side spring pad on the front axle.

You’re usually pretty safe following suspension system manufacturer recommendations. When folks start trying to mix and match components or install incomplete systems is where you’ll usually see issues. Most manufactures will typically give you maximum tire size recommendations for a particular lift along with wheel offset recommendations. These recommendations are based on their testing which includes articulation limits.

 

[domingjm]

What ever the ‘special sauce’ is…differs from manufacturer to manufacturer. Ultimately, the axle has high points, upper control arm mounts for example, and they can only go up so far before making contact with the motor components…and tires with fenders. On the Mopar kit for example, their 2” lift has 2” bump stop extensions that mount to the spring pad on the axle side spring pad on the front axle.

You’re usually pretty safe following suspension system manufacturer recommendations. When folks start trying to mix and match components or install incomplete systems is where you’ll usually see issues. Most manufactures will typically give you maximum tire size recommendations for a particular lift along with wheel offset recommendations. These recommendations are based on their testing which includes articulation limits.

That's very helpful. Thanks.

 

[Giersz]

Apologies for my naivety, I'm in the process of learning all of this terminology. Does this have implications for a run of the mill 2.5" suspension lift kit?

bump stops are used to:
1. Make sure axle will not hit engine parts
2. Tires will not hit fender

When you add lift you have to deal with following:
1.Lift will allow more flex so tire can go a bit higher on full flex. This can be big problem when adding wider tires and rims wit negative offset
2. You make lift to add bigger tire - bigger tire can hit fenders

This is why you want to add more bumpstops. If you make lift and keep factory wheels than in most cases you do not need any additional bumpstops. Factory bumpstops will keep your axle away from any engine parts.
Adding bigger wheels will require changing fenders or adding bumpstops.

Most companies in lift installation mamuals give recomended bumpstops size for bigger wheels, but they do not care of it is Diesel or Gas.
As far as I know the only company that gives detiled instuctions to gas or diesel version is Teraflex.
Basically you can do 1.35 inch less bumpstops than Gas models because you have longer tubes.
So when adding any lift and bigger tires to Diesel with less bumpstops will compensate longer jounce tubes and make your suspension work exactly rhe same as in Gas models.

 

[domingjm]

As I stated before I ended up installing Sumo Springs bump-stops and Tereflex 1-1/2 spacer lift in front. I also installed the Rear 3/4 in spacer to level and added the rear Sumo spring bump-stops. Everything drives the same on pavement but on dirt or any bumps it is far smoother. The Sumo springs "hit" sooner than the old bump-stops but it smooths everything out. You can't even feel it touch but I know they do because there is only 1-1/2 of space before they do.
I am very happy to get the better ride without lifting much.

These rear polyurethane spacers (e.g., Daystar, Teraflex)....any reason to suspect they'd be insufficient? I'd like to add less than 1" in the rear, so they'd be perfect (and cheap), but it just feels counterintuitive that two pieces of plastic would be able to support the forces from offroading and trailering. And frankly, I'm always expecting anything Jeep related to be over $500 ?. Consensus is they're fine? Sorry for a bit of a hijack.

Edit: looks like I need exactly 1" rear. Can't seem to find one in that height though. Any suggestions?

 

[Dougstdig]

So the planets aligned, the rear shock we’ve been waiting on for two months mysteriously appeared and the dealer was able to get me in to install the TSB repair on Saturday. I was at the dealer for approximately an hour and a half and they were great.

My very first impression was pulling out of the dealership onto a 55 mile an hour road. When I pulled out I noticed crossing the transition onto the road the vehicle was not near as squishy. It didn’t wallow around like it normally did and this is absolutely not to say that it was stiff. On road, it seemed the shocks may have higher pressure and definitely changed valving/shim stack's. Again, the suspension is not harsh at all, but it is more controlled without being floaty.

I got back home earlier than anticipated and didn’t want to be stuck in the house, so I made yet another trip down to Ocala National Forest. I drove down the main pipeline where there’s a combination of hard pack sand and seemingly bottomless sugar sand pits camouflaged by shadows of trees hiding abrupt mini trenches. Two weekends ago I had to drive no faster than 5 miles an hour or I’d easily bottom out time after time with the dreaded steel on steel loud bang. Yesterday was a much different story. It handled the irregularities much like I would’ve anticipated. Granted now my front end is squatting between an inch and inch and a half due to the winch plate and 12,000 pound winch riding in between the frame rails. I intentionally drove too fast forcing bottom outs to occur. They felt much like they should with a short yeah progressive muffled thud. On two different occasions I got a tad bit too enthusiastic about my testing and the front end actually was catching some air. Again, it wasn’t brutally harsh, but it was enough to let me know I needed to back it down. I came up on a husband and wife driving an JL who where interested in what I was doing. After explaining it to them, I got ducked for the first time…lol.

Now that the suspension is as it should have been leaving the factory, it’s time to put some elevation on her.

 

[Mike-len]

So I haven’t seen anything lately on this thread. Is this issue happening on the 2022 JTRD? I didn’t feel like reading through 58 pages after reading through about 20.

 

[Almost]

So I haven’t seen anything lately on this thread. Is this issue happening on the 2022 JTRD? I didn’t feel like reading through 58 pages after reading through about 20.

Depends on your build date - was it after 2/25/22? If so you are good and got the updated shocks/bumps off the assembly line. That said, in my case, it only made it about 50% better. My Jeep went from bottoming out at 10 mph over a speed bump to 15-16 mph after the fix. I will be adding the front clayton springs they have to fix the issue and make it a little bit better. Trying to keep it stockish height for now for the wife with 35s otherwise, I would just lift it.

 

[Rusty PW]

So I haven’t seen anything lately on this thread. Is this issue happening on the 2022 JTRD? I didn’t feel like reading through 58 pages after reading through about 20.

The up date happened with the 2/17/22 and newer. Mine is 2/17/22. So I have the the up dated stuff. It still bottomed out some. I have the Clayton springs installed. They made it even better. They're a heavy spring rate and raised the front about 1". When Clayton came out with the springs, i was a Beta tester for them.

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